TEMPE, Ariz. — Arizona Cardinals All-Pro cornerback Patrick Peterson, a former LSU star, has been suspended for the first six games of the 2019 season for violating the NFL's performance-enhancing drug policy.

The NFL did not specify Thursday which illegal substance Peterson allegedly used.

Peterson can participate in all offseason workouts and preseason games. He will be eligible to return Oct. 14, before Arizona's game against the New York Giants.

"Patrick recognizes how disappointing this is for everyone in the organization as well as our fans," the Cardinals said in a statement. "As we all do, he understands that regardless of intent he is ultimately responsible for everything he puts in his body. Our coaching staff and our players are now aware that we will have to play the first six games without Patrick and they understand they have to rise to the challenge that it presents."

Peterson starred as a defensive back and kick returner for LSU from 2008-'10 before the Cardinals selected him No. 5 overall in the 2011 draft.

Peterson still holds an LSU record for return yards in a single game. He collected 257 yards on punt and kick returns in the 2010 season opener against North Carolina, including an 87-yard punt return for a touchdown.

Peterson is still one of the NFL's best cornerbacks at 28. The fifth overall pick of the 2011 draft, he has 23 career interceptions despite teams rarely testing him.

Peterson is a three-time All-Pro and he holds the franchise record with eight Pro Bowl appearances, a streak that will likely come to an end with his suspension.

Peterson demanded a trade last season before apologizing. He posted a few cryptic messages on social media last month while deleting all mentions of the Cardinals in his profiles.

The Cardinals have been searching for a cornerback to play opposite Peterson almost since he came into the league. Arizona signed veteran Robert Alford as a free agent this offseason and used a second-round draft pick this year on Washington cornerback Byron Murphy.